In high speed, precision presses, such as of the type disclosed in U.S. Pat. No. 3,213,729 issued Oct. 26, 1965 to Koch, the press head and the opposed, fixed position die support or press anvil are normally accurately aligned along a horizontal press axis. The anvil is maintained in a stationary position and the press head reciprocates along the press axis towards and away from the anvil. Cooperating die members are removabley fastened to each of the head and the anvil to stamp sheet metal located between the die members.
In such type presses, which are of relatively low power or tonage, but which are extremely accurate in operation and are particularly useful for stamping very thin sheet metal parts, it is necessary to maintain highly accurate alignment between the die members. This requires maintaining accurate alignment of the press head and anvil or fixed die support along the press axis.
In commercially available presses, such as of the type described in the above patent, the anvil is normally removable from the press head in order to service or replace die members. Ordinarily the anvil is fastened to the press bed by means of screws which, when the anvil is mounted along a horizontal axis, extend downwardly into the bed. Thus, the fastening screws for the anvil normally extend transversely of the press axis. Consequently, the degree of tightening of the fastening screws effects the alignment of the anvil relative to the press axis. For example, over-tightening of the fastening screws can result in the die member carried by that anvil being too low relative the press axis. Under-tightening can result in the die member being too high. Either results in misalignments between the opposed die members. Such misalignment can cause excessive die wear, breakage of the die parts and inaccuracies in stamping thin sheet metal.
In some horizontal presses, the anvil or fixed position die support is in the form of a body member having a die receiving socket, with the body carried upon a base that is fastened by screws to the bed. As in the use described above, the screws are transversely arranged, i.e., they screw the base down against the bed. The body member is pivotally secured to the base, as for example, by horizontally extending trunions fitted into pivot sockets formed on the base. The body can be pivoted into alignment with the press head for stamping or pivoted so that its die receiving socket opens upwardly for removal and replacement of the die members fitted within the socket. A suitable locking means holds the body in the press head alignment position. However, in this instance, die misalignments also occur due to the tolerances or looseness required between the trunions and sockets and also due to the body locking means. Moreover, the base fastening screws likewise cause some misalignments.
Where the sheet metal being stamped is of thin gauge, as for example, less than one thousanths of an inch in thickness, the maintenance of axial alignment of the head, anvil and the opposed die members, is critical. Even slight misalignments resulting from over-tightening or under-tightening of the fastening screws or the body pivots, seriously effect the die operation, die life and stamping accuracy.
Consequently, the invention herein is concerned with providing a means for fastening the die support or anvil upon the press bed in a manner which is unaffected by the amount of tightening of the fastening screws and simultaneously, provides a simple system for moving the fixed die support into a position where its die members can be easily removed and replaced.